2000 rpm mis-fire
Thread Starter
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Trailering
Joined: Apr 2024
Posts: 20
Likes: 2
2000 rpm mis-fire
First time post for me.
Loved this forum as a watcher and now member.
I have a 1989 Ford f159 4x4 with 4.9 engine. Motor is a fresh rebuild. it start and runs great until i rev the motor over 2000 rpm. That's when thee motor stumbles all over it self . the tach goes wild sweeping the entire dial and the truck jerks. this does not stop until i let off and get below 2000 rpm then it run fine. I have thrown the parts cannon at it: new distributor, coil, MAP, TPS, ECM and both high and low pressure fuel pumps. Nothing changes the problem.
it's getting frustrating. Has anyone else had this issue and fix it?
Loved this forum as a watcher and now member.
I have a 1989 Ford f159 4x4 with 4.9 engine. Motor is a fresh rebuild. it start and runs great until i rev the motor over 2000 rpm. That's when thee motor stumbles all over it self . the tach goes wild sweeping the entire dial and the truck jerks. this does not stop until i let off and get below 2000 rpm then it run fine. I have thrown the parts cannon at it: new distributor, coil, MAP, TPS, ECM and both high and low pressure fuel pumps. Nothing changes the problem.
it's getting frustrating. Has anyone else had this issue and fix it?
Thread Starter
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Trailering
Joined: Apr 2024
Posts: 20
Likes: 2
Yes
yes. And just to be sure my son had a good one so I swapped it out. No change. Then put in known good distributor from running motor. No change😤
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
Disconnect your spout connector and try reving it again. The fact that your tachometer goes nuts tells me that your ICM is asking for more spark than the engine can handle, possible multiple sparks per cylinder, per firing order.
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Trailering
Joined: Apr 2024
Posts: 20
Likes: 2
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PCM and ECM are the same reference. I believe the term PCM came into play when the E4OD transmission was introduced. PCM = Powertrain Control Module because it now controls the engine and transmission. Someone else may have a different viewpoint.
Seems odd that Code 58 is not listed for this vintage truck. Code 67 can be caused by an out of adjustment MLPS, on 6 cylinder trucks the clutch pedal was not depressed, or the A/C circuit was energized during the KOEO tests. This can also be triggered by having the selector **** in the Defrost position.
Code 98 is Hard Fault present or Transmission EPC circuit/solenoid failure for trucks with an E4OD.
Seems odd that Code 58 is not listed for this vintage truck. Code 67 can be caused by an out of adjustment MLPS, on 6 cylinder trucks the clutch pedal was not depressed, or the A/C circuit was energized during the KOEO tests. This can also be triggered by having the selector **** in the Defrost position.
Code 98 is Hard Fault present or Transmission EPC circuit/solenoid failure for trucks with an E4OD.
Cargo Master
Joined: Aug 2003
Posts: 3,263
Likes: 92
From: BC Canada
How about finding some one with a scope and record the ignition wave form.. so we can see if it electrical or a rabbit hole..
Had one here recently that turned out to be a plugged fuel filter, lean at load..
Had one here recently that turned out to be a plugged fuel filter, lean at load..
